Fuel cell and method for controlling same

• US RE39,556 E1
• Filed: 10/19/2001
• Issued: 04/10/2007
• Est. Priority Date: 11/20/1997
• Status: Expired due to Term

• Current Assignee: Emergent Power Inc. (Plug Power Inc.)
• Original Assignee: Relion Incorporated (Plug Power Inc.)
• Inventors: Lott, David R., Fuglevand, William A., Lloyd, Greg A., DeVries, Peter D., Scartozzi, John P.
• Primary Examiner(s): Kalafut; Stephen J.
• Application Number:
  US10/014,033
• Time in Patent Office: 1,999 Days
• Field of Search: 429/13, 429/22, 429/23, 429/24, 429/25
• US Class Current: 429/431
• CPC Class Codes: H01M 2008/1095 Fuel cells with polymeric electrolytes
• CPC Class Codes: H01M 2300/0082 Organic polymers
• CPC Class Codes: H01M 8/026 characterised by grooves, e.g. their pitch or depth
• CPC Class Codes: H01M 8/0265 the reactant or coolant channels having varying cross sections
• CPC Class Codes: H01M 8/04007 related to heat exchange
• CPC Class Codes: H01M 8/04014 Heat exchange using gaseous fluids; Heat exchange by combustion of reactants
• CPC Class Codes: H01M 8/04089 of gaseous reactants
• CPC Class Codes: H01M 8/04097 with recycling of the reactants H01M8/04119, H01M8/04104 take precedence
• CPC Class Codes: H01M 8/04223 during start-up or shut-down; Depolarisation or activation, e.g. purging; Means for short-circuiting defective fuel cells
• CPC Class Codes: H01M 8/04291 Arrangements for managing water in solid electrolyte fuel cell systems H01M8/04119 takes precedence
• CPC Class Codes: H01M 8/04552 of the individual fuel cell
• CPC Class Codes: H01M 8/04559 of fuel cell stacks
• CPC Class Codes: H01M 8/04582 of the individual fuel cell
• CPC Class Codes: H01M 8/04589 of fuel cell stacks
• CPC Class Codes: H01M 8/04753 of fuel cell reactants
• CPC Class Codes: H01M 8/0494 of fuel cell stacks
• CPC Class Codes: H01M 8/04955 Shut-off or shut-down of fuel cells
• CPC Class Codes: H01M 8/1004 characterised by membrane-electrode assemblies [MEA] H01M8/12 takes precedence
• CPC Class Codes: H01M 8/241 with solid or matrix-supported electrolytes
• CPC Class Codes: H01M 8/2457 with both reactants being gaseous or vaporised
• CPC Class Codes: H01M 8/247 : Arrangements for tightening a stack, for accommodation of a stack in a tank or for assembling different tanks

Abstract

The present invention relates to an improved fuel cell and method of controlling same having an anode and a cathode which produces an electrical current having a given voltage and current output and which includes a controller electrically coupled with the fuel cell and which shunts the electrical current between the anode and the cathode of the fuel cell. The invention also discloses a method for controlling the fuel cell having an anode, a cathode and a given voltage and current output and which include determining the voltage and current output of the fuel cell; and shunting the electrical current between the anode and cathode of the fuel cell under first and second operation parameters.

Claims

1. A fuel cell having an anode and a cathode and which produces an electrical current having a voltage output, comprising:

a controller electrically coupled with the fuel cell and which shunts the electrical current between the anode and cathode of the fuel cell;

a supply of fuel gas disposed in fluid flowing relation relative to the anode of the fuel cell; and

a valve disposed in fluid flowing control relative to the supply of fuel gas, and wherein the controller is coupled in controlling relation relative to the valve.

2. A fuel cell as claimed in claim 1, wherein the controller further comprises voltage and current sensors which are disposed in voltage and current sensing relation relative to the electrical power output of the fuel cell.

3. A fuel cell as claimed in claim 2, wherein the controller further comprises an electrical switch having open and closed electrical conditions, and wherein the controller upon sensing, by the voltage and current sensors, a voltage and current output of the fuel cell, adjusts the valve into a fluid metering relationship relative to the supply of fuel gas, and the electrical switch is positioned in the open or closed electrical condition, and wherein the fuel cell, in the second condition, has a duty cycle.

4. A fuel cell as claimed in claim 3, wherein the controller, in a first condition, shunts current between anode and cathode of the fuel cell when the electrical switch is in the closed electrical condition, and wherein the controller simultaneously causes the valve to terminate the supply of fuel gas to the fuel cell, and wherein the electrical switch when placed in the open electrical condition by the controller also causes the valve to be placed in a condition which allows the substantially continuous supply of fuel gas to the fuel cell.

5. A fuel cell as claimed in claim 4, wherein the controller, in a second condition, shunts current during the duty cycle between the anode and cathode of the fuel cell when the electrical switch is in the closed electrical condition, and wherein the controller maintains the valve in a condition which allows the substantially continuous delivery of the fuel gas to the fuel cell during the opening and closing of the electrical switch.

6. A fuel cell as claimed in claim 4, wherein the fuel cell has performance parameters comprising current and voltage outputs, and wherein the first condition, the voltage and current output of the fuel cell is less than the performance parameters;

and wherein in the second condition, the electrical switch periodically opens and closes during the duty cycle to cause a resulting increase in the electrical power output of the fuel cell.

7. A fuel cell as claimed in claim 4, wherein the fuel cell has performance parameters comprising current and voltage outputs, and wherein in the first condition, the performance parameters are declining.

8. A fuel cell as claimed in claim 4, wherein the fuel cell has performance parameters comprising current and voltage outputs at a full rated current, and wherein in the first condition the performance parameters are declining or in a range of less than about 0.4 volts.

9. A fuel cell as claimed in claim 4, wherein the fuel cell has performance parameters comprising current and voltage outputs, and wherein in the second condition the fuel cell has an operating cycle of about 0.01 seconds to about 4 minutes, and wherein the duty and operating cycles are individually and selectively adjusted by the controller at least in part by reference to the performance parameters of the fuel cell.

10. A fuel cell as claimed in claim 4, wherein the fuel cell has performance parameters comprising current and voltage outputs, and wherein in the second condition the fuel cell has an operating cycle of about 0.01 seconds to about 4 minutes, and wherein the duty and operating cycles are individually selectively adjusted by the controller at least in part by reference to the declining performance parameters of the fuel cell in relative comparison to the performance parameters of other fuel cells.

11. A fuel cell as claimed in claim 4, wherein the fuel cell is serially electrically coupled with another fuel cell.

12. A fuel cell as claimed in claim 11, wherein in the second condition, the fuel cell has a duty cycle and an operating cycle of about 0.01 seconds to about 4 minutes, and wherein the controller is electrically coupled with each of the fuel cells to shunt electrical current during the duty cycle between the anode and cathode of each of the fuel cells, and wherein the controller shunts the individual fuel cells in a given repeating pattern.

13. A fuel cell as claimed in claim 12, wherein in the second condition, the controller which is electrically coupled with each of the fuel cells periodically shunts electrical current during the duty cycle between the anode and cathode of each of the fuel cells to achieve a resulting increased electrical power output from the serially electrically coupled fuel cells, and wherein the given repeating pattern of the controller comprises serially shunting the individual fuel cells in the repeating pattern.

14. A fuel cell as claimed in claim 13, wherein in the second condition, the duty and operating cycles are individually selectively adjusted to optimize the electrical power output of the fuel cells, and wherein the electrical power output of the serially electrically connected fuel cells increases by at least about 5 percent;

and wherein the duration of the shunting during the duty cycle is less than about 20% of the operating cycle.

15. A fuel cell as claimed in claim 14, wherein the electrical switch comprises a field effect transistor, and wherein the controller which is operable to shunt the electrical current between the anode and cathode of each of the fuel cells further comprises a passive by-pass electrical circuit which operates upon failure of the field effect transistor to shunt current between the anode and cathode of each of the fuel cells.

16. A fuel cell as claimed in claim 15, wherein the passive by-pass electrical circuit comprises a diode.

17. A fuel cell having an anode and cathode and which produces electrical power having a current and voltage output, comprising:

a supply of fuel gas disposed in fluid flowing relation relative to the anode of the fuel cell;

a valve disposed in fluid flowing controlling relation relative to the supply of fuel gas to meter the fuel gas to the anode of the fuel cell; and

a controller electrically coupled with the fuel cell and disposed in controlling relation relative to the valve, and wherein the controller adjusts the valve into a given fluid metering relationship relative to the supply of fuel gas, and the controller shunts current between the anode and cathode of the fuel cell.

18. A fuel cell as claimed in claim 17, wherein the controller further comprises voltage and current sensors which are disposed in sensing relation relative to the electrical power output of the fuel cell;

and an electrical switch which has open and closed electrical conditions, and wherein the controller causes the electrical switch to move between the open and closed electrical conditions.

19. A fuel cell as claimed in claim 18, wherein the controller, in a first condition, shunts current between the anode and cathode of the fuel cell when the electrical switch is in the closed electrical condition, and wherein the controller simultaneously causes the valve to terminate the supply of fuel gas to the fuel cell, and wherein the electrical switch when placed in the open electrical condition by the controller also causes the valve to be placed in a condition which allows the substantially continuous supply of fuel gas to the fuel cell.

20. A fuel cell as claimed in claim 19, wherein the controller, in a second condition, shunts current between the anode and cathode of the fuel cell when the electrical switch is placed in the closed electrical condition, and wherein the controller maintains the valve in a condition which allows the substantially continuous delivery of the fuel gas to the fuel cell during the open and closing of the electrical switch, and wherein the fuel cell in the second condition has a duty cycle.

21. A fuel cell as claimed in claim 20, wherein the fuel cell has performance parameters comprising current and voltage outputs, and wherein in the first condition, the voltage output of the fuel cell is less than the performance parameters;

and wherein in the second condition, the electrical switch periodically opens and closes during the duty cycle to cause a resulting increase in the electrical power output of the fuel cell.

22. A fuel cell as claimed in claim 20, wherein the fuel cell has performance parameters comprising current and voltage outputs, and wherein in the first condition, the performance parameters are declining.

23. A fuel cell as claimed in claim 20, wherein the fuel cell has performance parameters comprising current and voltage outputs at a full rated current, and wherein in the first condition the performance parameters are declining or in a range of less than about 0.4 volts.

24. A fuel cell as claimed in claim 20, wherein the fuel cell has performance parameters comprising current and voltage outputs, and wherein in the second condition the fuel cell has an operating and duty cycle, and wherein the operating and duty cycles are individually and selectively adjusted by the controller at least in part by reference to the performance parameters of the fuel cell.

25. A fuel cell as claimed in claim 20, wherein the fuel cell has performance parameters comprising current and voltage outputs, and wherein in the second condition the fuel cell has a duty cycle, and an operating cycle of about 0.01 seconds to about 4 minutes, and wherein the operating and duty cycles are individually and selectively adjusted by the controller at least in part by reference to the declining performance parameters of the fuel cell in relative comparison to the performance parameters of other fuel cells.

26. A fuel cell as claimed in claim 20, wherein the fuel cell is serially electrically coupled with another cell.

27. A fuel cell as claimed in claim 26, wherein the controller is electrically coupled with each of the fuel cells to shunt current between the anode and cathode of each of the fuel cells.

28. A fuel cell as claimed in claim 27, wherein the fuel cell has a duty cycle and an operating cycle of 0.01 seconds to about 4 minutes, and wherein in the second condition, the controller which is coupled with each of the fuel cells periodically shunts current during the duty cycle between anode and cathode of each of the fuel cells to cause a resulting increased electrical power output from the serially electrically coupled fuel cells.

29. A fuel cell as claimed in claim 28, wherein in the second condition, the duty and operating cycles are individually selectively adjusted to optimize the electrical power output of the respective fuel cells;

and wherein the electrical power output of the serially electrically connected fuel cells increases by at least about 5 percent; and

wherein the duration of the shunting during the duty cycle is less than about 20% of the operating cycle.

30. A fuel cell as claimed in claim 29, and wherein the electrical switch comprises a field effect transistor, and wherein the controller which is operable to shunt current between the anode and cathode of each of the serially connected fuel cells further comprises a passive by-pass electrical circuit which operates upon failure of the field effect transistor to shunt current between the anode and cathode of each of the fuel cells.

31. A fuel cell as claimed in claim 30, and wherein the passive by-pass electrical circuit comprises a diode, and the controller is an automated intelligent controller.

32. A fuel cell having an anode, a cathode and which produces electrical current having an electrical power output, comprising:

a membrane having opposite sides, and wherein the anode is mounted on one side of the membrane, and the cathode is mounted on the side of the membrane opposite to the anode;

a supply of fuel gas disposed in fluid flowing relation relative to the anode, and a supply of an oxidant gas disposed in fluid flowing relation relative to the cathode;

voltage and current sensors which are individually electrically coupled with the anode and cathode;

a valve disposed in fluid flowing controlling relation relative to the supply of fuel gas to meter the supply of fuel gas to the fuel cell;

an electrical switch electrically coupled with the anode and cathode and which can be placed into an open and closed electrical condition;

a controller coupled with the electrical switch, valve and the voltage and current sensors, the controller upon sensing a voltage and current at the voltage and current sensors causing the valve to be adjusted into a fluid metering relationship relative to the supply of fuel gas, and the electrical switch to assume a predetermined open or closed electrical condition.

33. A fuel cell as claimed in claim 32, wherein the controller, in a first condition, shunts current between the anode and cathode of the fuel cell when the electrical switch is in the closed electrical condition, and wherein the controller simultaneously causes the valve to terminate the supply of fuel gas to the fuel cell, and wherein the electrical switch when placed in the open electrical condition by the controller causes the valve to be placed in a condition which allows the substantially continuous supply of fuel gas to the anode of the fuel cell.

34. A fuel cell as claimed in claim 33, wherein the controller, in a second condition, shunts current between the anode and cathode of the fuel cell when the electrical switch is placed in the closed electrical condition, and wherein the controller maintains the valve in a condition which allows the substantially continuous delivery of the fuel gas to the fuel cell during the open and closing of the electrical switch, and wherein the fuel cell, in the second condition, has a duty and operating cycle.

35. A fuel cell as claimed in claim 34, wherein the fuel cell has performance parameters comprising current and voltage outputs, and wherein in the first condition, the voltage output of the fuel cell is less than the performance parameters;

and wherein in the second condition, the electrical switch periodically opens and closes during the duty cycle to increase the resulting electrical power output of the fuel cell.

36. A fuel cell as claimed in claim 34, wherein the fuel cell has performance parameters comprising current and voltage outputs, and wherein in the first condition, the performance parameters are declining.

37. A fuel cell as claimed in claim 34, wherein the fuel cell has performance parameters comprising current and voltage outputs at a full rated current, and wherein in the first condition the performance parameters are declining or in a range of less than about 0.4 volts.

38. A fuel cell as claimed in claim 34, wherein the fuel cell has performance parameters comprising current and voltage outputs, and wherein in the second condition the operating cycle is about 0.01 seconds to about 4 minutes, and wherein the duty and operating cycles are individually and selectively adjusted by the controller at least in part by reference to the performance parameters of the fuel cell.

39. A fuel cell as claimed in claim 34, wherein the fuel cell has performance parameters comprising current and voltage outputs, and wherein in the second condition the operating cycle is about 0.01 seconds to about 4 minutes, and wherein the duty and operating cycles are individually and selectively adjusted by the controller at least in part by reference to the declining performance parameters of the fuel cell in relative comparison to the performance parameters of other fuel cells.

40. A fuel cell as claimed in claim 34, wherein the fuel cell is serially electrically coupled with another fuel cell.

41. A fuel cell as claimed in claim 40, wherein the controller is electrically coupled with each of the fuel cells to shunt current between the anode and cathode of each of the fuel cells.

42. A fuel cell as claimed in claim 41, wherein in the second condition, the controller which is coupled with the anode and cathode of each of the fuel cells shunts current during the duty cycle between the anode and cathode of the respective fuel cells to achieve increased electrical power output from the serially electrically coupled fuel cells.

43. A fuel cell as claimed in claim 42, wherein in the second condition, the duty and operating cycles are individually and selectively adjusted to optimize the electrical power output of the responsive fuel cells;

and wherein the electrical power output of the serially electrically connected fuel cells increases by at least about 5%; and

wherein the duration of the shunting during the duty cycle is less than about 20% of the operating cycle.

44. A fuel cell having an anode, a cathode and which produces a current having an electrical power output, comprising:

a membrane having opposite sides, and wherein the anode is mounted on one side, of the membrane, and the cathode is mounted on the side of the membrane opposite to the anode;

a supply of fuel gas disposed in fluid flowing relation relative to the anode, and a supply of an oxidant gas disposed in fluid flowing relation relative to the cathode;

voltage and current sensors which are individually electrically coupled with the anode and cathode;

a valve disposed in fluid flowing controlling relation relative to the supply of fuel gas to meter the supply of fuel gas to the fuel cell;

an electrical switch electrically coupled with the anode and cathode and which can be placed into an open and closed electrical condition; and

a controller coupled with the electrical switch, valve and the voltage and current sensors, the controller upon sensing a voltage and current at the voltage and current sensors causing the valve to be adjusted into a fluid metering relationship relative to the supply of fuel gas, and the electrical switch to assume an open or closed electrical condition, and wherein the controller, in a first condition, shunts current between the anode and cathode of the fuel cell when the electrical switch is in the closed electrical condition, and simultaneously causes the valve to terminate the supply of fuel gas to the anode of the fuel cell, and wherein the electrical switch when placed in the open electrical condition by the controller causes the valve to be placed in a condition which allows the substantially continuous supply of fuel gas to the anode of the fuel cell; and

wherein the controller, in a second condition, shunts current between the anode and cathode of the fuel cell when the electrical switch is placed in the closed electrical condition, and simultaneously maintains the valve in a condition which allows the substantially continuous delivery of the fuel gas to the fuel cell to the anode during the opening and closing of the electrical switch.

45. A fuel cell as claimed in claim 44, wherein the fuel cell in the first and second conditions has performance parameters comprising selected current and voltage outputs, and wherein the first condition, the voltage output of the fuel cell is less than the performance parameters;

and wherein the fuel cell has a duty cycle, and wherein in the second condition, the electrical switch periodically opens and closes during the duty cycle to cause a resulting increase in the electrical power output of the fuel cell.

46. A fuel cell as claimed in claim 44, wherein the fuel cell has performance parameters comprising current and voltage outputs, and wherein in the first condition, the parameters are declining.

47. A fuel cell as claimed in claim 44, wherein the fuel cell has performance parameters comprising current and voltage outputs at a full rated current, and wherein in the first condition the performance parameters are declining or in a range of less than about 0.4 volts.

48. A fuel cell as claimed in claim 44, wherein the fuel cell has performance parameters comprising selected current and voltage outputs, and wherein in the second condition the fuel cell has an operating cycle of about 0.01 seconds to about 4 minutes, and wherein the duty and operating cycles are individually and selectively adjusted by the controller at least in part by reference to the performance parameters of the fuel cell.

49. A fuel cell as claimed in claim 44, wherein the fuel cell has performance parameters comprising current and voltage outputs, and wherein in the second condition the fuel cell has an operating cycle of about 0.01 seconds to about 4 minutes, and wherein the duty and operating cycles are individually and selectively adjusted by the controller at least in part by reference to the declining performance parameters of the fuel cell in relative comparison to the performance parameters of other fuel cells, and wherein the duration of the shunting during the duty cycle is less than about 20% of the operating cycle.

50. A fuel cell as claimed in claim 44, wherein the fuel cell has a duty cycle and an operating cycle of about 0.01 seconds to about 4 minutes;

and wherein the electrical power output of the serially electrically connected fuel cells increases by at least about 5%.

51. A fuel cell as claimed in claim 44, wherein the fuel cell is serially electrically coupled with another fuel cell.

52. A fuel cell as claimed in claim 44, wherein the controller is electrically coupled with the anode and cathode of each of the fuel cells to shunt current between the anode and cathode of each of the fuel cells.

53. A fuel cell as claimed in claim 44, wherein the controller which is coupled with each of the fuel cells periodically opens and closes the electrical switch to shunt current between the anode and cathode of each of the fuel cells to cause a resulting increased electrical power output from the serially electrically coupled fuel cells.

54. A fuel cell as claimed in claim 44, wherein the electrical switch comprises a field effect transistor, and wherein the controller further comprises a passive by-pass electrical circuit which operates upon failure of the field effect transistor to shunt current between the anode and cathode of each of the fuel cells.

55. A fuel cell as claimed in claim 54, wherein the by-pass electrical circuit comprises a diode.

56. A plurality of fuel cells which are serially electrically connected together and which individually produce voltage and current outputs comprising:

a membrane having opposite sides and which is made integral with each of the fuel cells, and wherein an anode is mounted on one side of the membrane, and a cathode is mounted on the side of the membrane opposite to the anode;

a supply of fuel cell disposed in fluid flowing relation relative to the anode of each of fuel cells, and a supply of an oxidant fuel disposed in fluid flowing relation relative to the cathode of each of the fuel cells;

voltage and current sensors which are individually electrically coupled with the anode and cathode of each of the fuel cells and which sense the electrical power output of each of the fuel cells;

a valve disposed in fluid flowing controlling relation relative to the supply of fuel gas to meter the supply of fuel gas to each of the fuel cells. ;

an electrical switch electrically coupled with the anode and cathode of each of the fuel cells and which can be placed into an open and closed electrical condition; and

a controller coupled with each of the electrical switches, valves and the voltage and current sensors, the controller operable to adjust the respective valves into a fluid metering relationship relative to the supply of fuel gas, and one or more of the electrical switches to assume an open or closed electrical condition relative to one or more of the fuel cells under operational conditions, and wherein the controller, in a first operational condition, upon sensing, at one or more of the fuel cells of interest a voltage and current output at the voltage and current sensors electrically coupled with same, shunts current between the anode and cathode of the fuel cell of interest when the electrical switch is in the closed electrical condition, and wherein the controller simultaneously causes the valve which is coupled to the fuel cell of interest to terminate the supply of fuel gas to the anode of the fuel cell of interest, and wherein the electrical switch when placed in the open electrical condition by the controller causes the valve coupled to the fuel cell of interest to be placed in a condition which allows the substantially continuous supply of fuel gas to the fuel cell of interest; and

wherein the controller, in a second operational condition, shunts current between the anode and cathode of the fuel cell of interest when the electrical switch is placed in the closed electrical condition, and wherein the controller maintains the valve coupled with the fuel cell of interest in a condition which allows the substantially continuous delivery of the fuel gas to the fuel cell of interest during the open and closing of the electrical switch.

57. A fuel cell as claimed in claim 56, wherein the fuel cell has a duty and operating cycle, and wherein in the first and second conditions the fuel cell has performance parameters comprising selected current and voltage outputs, and wherein in the first condition, the current and voltage outputs of the fuel cell are less than the performance parameters;

and wherein in the second condition, the electrical switch periodically opens and closes during the duty cycle to increase the electrical power output of the fuel cell.

58. The fuel cell as claimed in claim 56, wherein the fuel cell has a duty and operating cycle, and wherein in the first and second conditions the fuel cell has performance parameters comprising a current and voltage output, and wherein in the first condition, the performance parameters are declining.

59. A fuel cell as claimed in claim 56, wherein the fuel cell has a duty cycle, and wherein in the first and second conditions, the fuel cell has performance parameters comprising current and voltage outputs at a full rated current, and wherein in the first condition the performance parameters are declining or in a range of less than about 0.4 volts.

60. A fuel cell as claimed in claim 56, wherein the fuel cell has a duty and operating cycle, and wherein in the first and second conditions the fuel cell has performance parameters comprising current and voltage outputs, and wherein the operating cycle is about 0.01 seconds to about 4 minutes, and wherein the duty and operating cycles are adjusted by the controller at least in part by reference to the performance parameters of the fuel cell.

61. A fuel cell as claimed in claim 56, wherein the fuel cell has a duty cycle, and wherein in the first and second conditions, the fuel cell has performance parameters comprising current and voltage outputs, and wherein in the second condition the fuel cell has an operating cycle of about 0.01 seconds to about 4 minutes, and wherein the duty cycle and operating cycle are individually and selectively adjusted by the controller at least in part by reference to the declining performance parameters of the fuel cell in relative comparison to the performance parameters of other fuel cells.

62. The fuel cell as claimed in claim 60, wherein in the second condition, the duty and operating cycles are individually selectively adjusted to optimize the electrical power output of the fuel cells, and wherein the electrical power output of the serially electrically connected fuel cell increases by at least about 5%;

and wherein the duration of the shunting during the duty cycle is less than about 20% of the operating cycle.

63. A fuel cell as claimed in claim 56, wherein the electrical switch comprises a field effect transistor, and wherein the controller further comprises a passive by-pass electrical circuit which operates upon failure of the field effect transistor to shunt current between the anode and cathode of each of the fuel cells.

64. A fuel cell as claimed in claim 56, wherein the by-pass electrical circuit comprises a diode.

65. A method for controlling a fuel cell which has an anode and a cathode, and a voltage and current output, comprising:

determining the voltage and current output of the fuel cell;

shunting electrical current between the anode and cathode of the fuel cell under operational conditions;

providing a supply of a fuel cell in fluid flowing relation relative to the anode of the fuel cell;

providing a valve disposed in fluid metering relation relative to the supply of the fuel gas; and

providing a controller which is electrically coupled with the anode and the cathode and which is effective to shunt the electrical current between the anode and the cathode, and which further is coupled in controlling relation relative to the valve.

66. A method as claimed in claim 65, and wherein the fuel cell has performance parameters, and wherein in a first condition the method further comprises:

determining by way of the controller the voltage and current output of the fuel cell;

adjusting the valve, by way of the controller, to terminate the flow of the fuel gas to the anode when the voltage and current outputs of the fuel cell are less than the performance parameters; and

shunting the current between the anode and the cathode by way of the controller.

67. A method as claimed in claim 66, wherein the fuel cell has performance parameters, and wherein in a second operational condition the method further comprises:

determining, by way of the controller, the voltage and current output of the fuel cell;

supplying the fuel cell substantially continuously with the fuel gas; and

periodically shunting the current between the anode and the cathode, by way of the controller, to cause a resulting increased electrical power output of the fuel cell, and wherein the periodic shunting of the current comprises the duty cycle of the fuel cell.

68. A method as claimed in claim 67, wherein in the second operational condition the controller periodically shunts the current between the anode and the cathode during an operating cycle which is about 0.01 seconds to about four minutes in duration.

69. A method as claimed in claim 68, wherein in the second operational condition, the duration of the shunting during the duty cycle is less than about 20% of the operating cycle.

70. A method as claimed in claim 69, wherein in the second operational condition the voltage output of the fuel cell increases by at least 5%.

71. A method for controlling a fuel cell which has an anode and a cathode, and a voltage and current output, comprising:

providing a supply of a fuel gas in fluid flowing relation relative to the anode of the fuel cell;

providing a valve disposed in fluid metering relation relative to the supply of the fuel gas;

providing a controller which is electrically coupled in voltage and current sensing relation with the anode and the cathode and which is effective to shunt the electrical current between the anode and the cathode, and which further is coupled in controlling relation relative to the valve;

determining by way of the controller whether the voltage and current output of the fuel cell has a voltage and current output;

after the step of determining the voltage and current output, adjusting the valve by way of the controller to terminate the flow of fuel gas to the anode if the voltage and current output is less than a predetermined amount, and shunting the electrical current by way of the controller between the anode and cathode of the fuel cell.

72. A method for controlling a fuel cell which has an anode, a cathode, a voltage and current output, and a duty and operating cycle, comprising:

providing a supply of a fuel gas in fluid flowing relation relative to the anode of the fuel cell;

providing a valve disposed in adjustable fluid metering relation relative to the supply of the fuel gas;

providing a controller which is electrically coupled in voltage and current sensing relation with the anode and the cathode and which is effective to shunt the electrical current during the duty cycle between the anode and the cathode of the fuel cell, and which further is coupled in controlling relation relative to the valve; and

after determining the voltage and current output of the fuel cell, and with the valve being maintained in a position which insures the substantially continuous supply of fuel gas to the anode of the fuel cell, periodically shunting, by way of the controller, the current between the anode and the cathode to cause a resulting increased electrical power output, and wherein the operating cycle is about 0.01 seconds to about 4 minutes, and wherein the duration of the shunting during the duty cycle is less than about 20% of the operating cycle.

73. A fuel cell having an anode, a cathode, and which produces an electrical current having a voltage output comprising:

a controller electrically coupled to the fuel cell and which periodically shunts the electrical current between the anode and cathode of the fuel cell, and wherein the fuel cell has an operating cycle and a duty cycle, and wherein the periodic shunting increases the electrical power output of the fuel cell, and the duration of the shunting during the duty cycle is less than 20% of the operating cycle.

74. A method of bypassing a failing fuel cell, in a fuel cell power system, the fuel cell having an anode, and a cathode, the method comprising placing a diode in parallel with the fuel cell, the diode having an anode, and a cathode by electrically coupling the anode of diode to the anode of the fuel cell, and electrically coupling the cathode of the diode to the cathode of the fuel cell, and wherein if the fuel cell fails, current flows from the anode of the fuel cell to the cathode of the fuel cell via the diode instead of through the fuel cell.

75. A fuel cell power system comprising:

a first fuel cell having an anode and a cathode;

a diode having an anode coupled to the anode of the first fuel cell and a cathode coupled to the cathode of the first fuel cell; and

a plurality of additional fuel cells electrically coupled with the first fuel cell, the additional fuel cells each having an anode and a cathode.

78. A fuel cell power system in accordance with claim 75 wherein the diode is a Shottky barrier diode.

76. A fuel cell power system comprising:

a first fuel cell having an anode and a cathode;

a diode having an anode coupled to the anode of the first fuel cell and a cathode coupled to the cathode of the first fuel cell;

a plurality of additional fuel cells electrically coupled with the first fuel cell, the fuel cells each having an anode and a cathode; and

a plurality of additional diodes having anodes electrically coupled to the anodes of the additional fuel cells, respectively, and having cathodes electrically coupled to the cathodes of the additional fuel cells, respectively.

79. A fuel cell power system in accordance with claim 76 wherein the first mentioned diode and the additional diodes are Shottky barrier diodes.

77. A fuel cell power system comprising:

a first fuel cell having an anode and a cathode;

a first diode having an anode coupled to the anode of the first fuel cell and a cathode coupled to the cathode of the first fuel cell;

a second fuel cell serially electrically coupled with the first fuel cell, the second fuel cell having an anode and a cathode; and

a second diode having an anode coupled to the anode of the second fuel cell and a cathode coupled to the cathode of the second fuel cell.

80. A fuel cell power system in accordance with claim 77 wherein the first and second diodes are Shottky barrier diodes.